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back to article Astronomers detect red giant survivor planet

Italian astronomers have detected a planet that survived the red giant expansion of its home star. The researchers say that the discovery could be a sneak peek at the fate that awaits the Earth, some four or five billion years from now. Artist's impression of the surviving planet. The surviving planet was discovered by an …

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Anonymous Coward

Batman

Is it me, or is the shadow of the caped crusader in the picture (top right, see the shadow of his horned cowl)

Also, where's the Paris Hilton angle? (heh)

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It's all a bit hypothetical...

.. as life will be gone from the earth in a billion or so years anyway.

I know it's a long time, but look at it this way: there isn't enough time to re-evolve to the present state from single cells, not even eukaryotes.

Still, it'll last *my* lifetime.

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Silver badge

Interesting find

But there are two points that have not been pointed out :

1) the planetary body has apparently retained its integrity, but that is a gaseous giant, not an Earth-type ball of rock, and

2) there is no way of knowing whether or not there was life on that planet, nor if that life has survived.

The prospect of our Earth orbiting 20000 miles from the surface of a red giant may be very romantic in the picture, but I doubt that anyone will be there to see the sights, much less set foot on what will certainly be a very hot - if not molten - surface.

On the other hand, what guarantee is there that the Earth's orbit will not change ? As the Sun grows in size, its density diminishes. Will that not have an effect on Earth's position ? Even if the overall mass stays somewhat stable, I cannot help but wonder if the spreading out of said mass will not have for effect to let Earth drift away somewhat.

Then again, being 100000 miles from a star's surface is probably not going to be a whole lot better than 20000.

Pascal.

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Bronze badge

Links + More Info + Red Giant Astrophysics

This appears to be the press release (in Italian):

http://www.inaf.it/ufficio-stampa/comunicati-stampa-del-2007/CS_27_130907/

English translation provided here (as PDF):

http://www.inaf.it/ufficio-stampa/comunicati-stampa-del-2007/folder_CS_27_130907/inaf-pr-peg-e.pdf/download

This seems to be the paper about the same planet:

http://arxiv.org/pdf/astro-ph/0703753

They were planning on integrating more data – so maybe its been revised before publication in Nature.

Anyway, based on the above, THE PLANET ORBITS at 1.7AU (about the distance of Mars), and HAS A MASS of at least 3.5 times that of Jupiter.

And for the record, a Red Giant doesn't exhaust *all* its Hyrdogen - just all that IN THE CORE, it then contracts, heats up, and begins fusing hydrogen in a shell around the core (now composed mainly of Helium) - try this link (with nice graphs):

http://www-astronomy.mps.ohio-state.edu/~pogge/Ast162/Unit2/lowmass.html

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Because every wobble in brightness of a star...

is of course a new extrasolar planet.

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Will Earth's orbit increase?

For Pascal: The mass of the Sun would remain more-or-less the same, and the centre of mass would stay in the same place. So, the Earth's orbit would not become enlarged simply due to the expansion of the Sun.

That's a simplification. Of course, the Sun "uses up" mass due to releasing energy through nuclear fusion. Also, when transitioning to the red giant stage it may shed some mass outwards. But, the effects of that on the orbit of the Earth would be minimal in comparison to the size of the Earth's orbit and the size of a red giant star.

This all assumes the Vogons don't demolish it first...

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Bronze badge

Chinny reckon

Seems a bit far fetched (no pun intended). I thought that we could only detect really massive planets close to the host star. This one is too small and too far away to be detectable by the current methods. The orbital period must be in the region of 2 of your Earth-years.

Are the researchers also claiming it as the most distant/smallest planet detected?

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amanfrommars RSVP

"...we expect Mercury and Venus to disappear in the sun’s envelope, whereas Mars should survive."

AMFM; can we crash at your place? Is 5 Billion years notice enough time to tidy up?

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an interesting theory...

about what happens to Earth was postulated in the Larry Niven novel "A World Out of Time". In the distant future, the sun's expansion forces some very clever engineering to move the earth. Essentially, a giant, remote controlled hydrogen/methane engine is placed in the upper atmosphere of Uranus or Neptune. The gas giant is then "piloted" in a flyby of Earth to move it into a more distant solar orbit. That's somewhat of an oversimplification, but it is definitely an interesting idea.

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Alien Survivor Will Be On with George Nit-Wit Noory radio Soon!

Did you hear the amazing LIAR guest that was on with Witless Noory last night (Tuesday). This BS artist, who claims he produced kiddie TV shows in a prior career, and some Japanese artist had visited many alien worlds in "out of body experience since he was 12! And of course that moron George Noory believed every word of it.

Well back to the point, proclamations like this discovery is as much bullshit as Noory's Coast to Ghost AM radio shows guests. NO ONE in astronomy has actually ever seen visually or with photography ANY extra-solar planet! That a stars wobble indicated 100% a planet, vs, another dwarf star or even a mini black hole is just as possble. The so-called planet is most likely a gas ball as Jupiter or Saturn etc is! Which means it has nothing to do in parallel, with Earth's future.

Go cure cancer, AIDs, MS, HUNGER, etc. instead of wasting our time and money on this speculative bullshit that saves NO ONE on Earth!

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Silver badge

@batman

He can breathe in space you know.

http://shortpacked.com/d/20050131.html

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Anonymous Coward

But what about...

...the Paris Hilton angle? What does she have to do with all this? Or is the planet made of her allocation of brain matter...?

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Replies from the observers

To Pascal; The orbit will indeed change; if the planet enters the atmosphere, friction will slow it down but the atmosphere is not dense enough in the bloated red giant to destroy it completely as long as the planet stays in the outer layers. At the end of the red giant phase, a significant amount of mass is ejected. In this special case the entire hydrogen envelope was lost (for unknown reasons) leaving only the helium-burning core behind with a thin hydrogen layer settling back down to envelope it. With the host star loosing at least half of its mass, the planets orbit must expand again to end up at the orbit where it is now seen. The exact amount depends on the inital stellar mass, but the planet could easily have been at or even inside an earth orbit during the red-giant phase.

To Alistar; The reason we can detect a planet at this distance is because the host star does a very rapid pulsation (the period is about 350 seconds), and thus provides its own clock. The first planet ever detected outside our solar system was around a pulsar using a similar technique. Almost all planets are now detected with spectroscopic instruments from the change in velocity of the host star. But photometric observations are much easier to obtain, and the observations that led to this discovery could be done with quite small telescopes.

The mass of the planet is (3.2+/-0.7)*sin(i) jupiter masses. Since we don't know the inclination angle i, 3.2 jupiter masses is the upper limit, as it would be the mass only if we see the system edge on. The period is 3.2 years and is quite accurately determined from our ~8 years of data.

If somebody wants to read the actual Nature paper but do not have a subscription, I can forward a PDF. It cannot be posted due to Nature copyright restrictions.

Roy Østensen

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Anonymous Coward

About the red giant

Once our sun turns into a red giant it will indeed lose mass and cause the earth orbit to shift outwards but not before the earth is superheated to the point of having its crust turned molten again. Also, during the final stages of red dwarfism, the sun would start casting off most of its atmosphere into space which in turn would rip the gaseous atmospheres off of our gas giant planets leaving them as cold dead rocks that would drift off towards deep space because the suns mass will no longer be enough to keep them in an orbit.

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Anonymous Coward

Title

Five billion years ? Whatever is around then will probably have developed something to back the planet out, ahead of the approaching sun edge. Too good a real estate to have it consigned to the furnace.

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Bronze badge

oh okay

Well I just went back to read Lucy's article again. It doesn't actually say the exoplanet was swallowed up by the red-giant and then spat out again, although I did mistakenly infer that.

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Dan

Mars and Earth

Bearing in mind that we on Earth are currently 1AU (Astral Unit) i.e 93million miles from our sun, being 20,000 or even 100,000 miles from the sun will not be a good thing for life on Earth. Mars is only another quarter to half an Astral Unit out from us, so whilst Mars as a planet may survive its unlikely any life on either planet will survive.

You'll have to start looking at the moons of Jupiter and Saturn. Europa and Io, or follow the edicts of many Science Fiction writers and have huge orbital space stations around Jupiter. Giant cities in space.

However as this will all be in 5 billion years and I doubt I will personally discover the secret to immortality in my lifetime.......Im not to fussed what happens then =)

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Anonymous Coward

The point of this is...?

Is this thinly veiled as an attempt to find life outside our solar system? If not, then finding planets that have done what this has done is little more than a hobby - and a chuffing expensive one at that. 5 billion years away? Come on - where's the relevance to our lives in that?

As someone said earlier, spend the money on something practical that affects us in our lifetime.

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Anonymous Coward

said one cave man to the other....

"are you still trying to find out how to extract metals from ores? You'll never do it in our lifetime. Do something practical and create better stone tools."

get the point?

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